Lag spikes when moving into an area

BRANCH: Live

REPORT:
This issue occurred at minor rates somewhat a year ago (last time I played), but after Gloomrot (and patches) it happens really frequently, heavily affecting the gameplay, especially if you're moving on a horse. It still happens when you just walk in basic vampire form.

When you move into chunks of the map you haven't visited yet in this particular game session and game tries to load it - it stutters heavily, freezing for a few seconds, while I get shanked by the mobs in a meantime. It's frustrating when you're riding a horse to a distant location and you drop from it while you lag, or even die due to it.

I'm not sure if it happens when you re-visit already unloaded and reloaded area, it's difficult to trace.

SERVER:
I play on a private server with my friend, who experiences the same issue.